U.S. patent application number 17/673256 was filed with the patent office on 2022-08-18 for injectable rib foot cleat.
The applicant listed for this patent is AIRBUS OPERATIONS LIMITED. Invention is credited to Martin CRIBB, Dave GIBBONS, Benjamin HUMPHRYS, James POWIS, Michael REILLY, Carl RICE, David Nathaniel WILSON.
Application Number | 20220258849 17/673256 |
Document ID | / |
Family ID | |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220258849 |
Kind Code |
A1 |
HUMPHRYS; Benjamin ; et
al. |
August 18, 2022 |
INJECTABLE RIB FOOT CLEAT
Abstract
A rib foot cleat for sealing around a stringer passing through a
rib mouse hole in an aircraft assembly. The rib foot cleat has a
body for attaching to a rib at a rib mouse hole and defines a cleat
channel configured to be arranged over the stringer. The rib foot
cleat also has an injection hole through the cleat body which is in
fluid communication with the cleat channel, to allow sealant
material to be injected through the injection hole in to the cleat
channel for sealing around the stringer.
Inventors: |
HUMPHRYS; Benjamin;
(Bristol, GB) ; GIBBONS; Dave; (Bristol, GB)
; RICE; Carl; (Bristol, GB) ; POWIS; James;
(Bristol, GB) ; CRIBB; Martin; (Bristol, GB)
; WILSON; David Nathaniel; (Bristol, GB) ; REILLY;
Michael; (Bristol, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS OPERATIONS LIMITED |
Bristol |
|
GB |
|
|
Appl. No.: |
17/673256 |
Filed: |
February 16, 2022 |
International
Class: |
B64C 3/18 20060101
B64C003/18; B64C 3/24 20060101 B64C003/24; F16B 11/00 20060101
F16B011/00; F16J 15/06 20060101 F16J015/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2021 |
GB |
2102308.0 |
Claims
1. A rib foot cleat for sealing around a stringer passing through a
rib mouse hole in an aircraft assembly, the rib foot cleat
comprising: a cleat body for attaching to a rib at a rib mouse hole
and defining a cleat channel configured to be arranged over a
stringer; and an injection hole through the cleat body in fluid
communication with the cleat channel and configured to allow a
sealant material to be injected through the injection hole into the
cleat channel for sealing around the stringer.
2. The rib foot cleat of claim 1, wherein the cleat channel is
U-shaped and terminates at a first channel opening rim on one side
of the cleat body and at a second channel opening rim on an
opposite side of the cleat body, and further comprising a channel
lip that extends at least partially around an interior of the cleat
channel adjacent the first and/or second channel opening rim.
3. The rib foot cleat of claim 2, wherein the channel lip is
configured to delimit the sealant material injected through the
injection hole.
4. The rib foot cleat of claim 3, wherein the channel lip is made
of sealant or a closed cell foam, and preferably the injectable
sealant material is curable to the lips.
5. The rib foot cleat of claim 4, wherein the sealant of the
channel lip is made from a curable material, such as silicone,
polyurethane, polysulphide, or silane-modified polymer.
6. The rib foot cleat of claim 1, wherein the cleat body further
comprises a first attachment flange for attaching the cleat body to
the rib, and/or a second attachment flange for attaching the cleat
body to a foot of the stringer.
7. The rib foot cleat of claim 1, wherein the cleat body is made of
metal.
8. An aircraft assembly comprising: a stringer reinforced cover and
a rib having a mouse hole with the stringer passing through the
mouse hole in the rib, and; a rib foot cleat according to claim 1,
arranged over the stringer at the rib mouse hole and with cured
sealant material inside the rib foot cleat which seals around the
stringer passing through the rib mouse hole.
9. The aircraft assembly according to claim 8, wherein the rib has
a plurality of mouse holes each having a respective stringer
passing through, and a respective rib foot cleat with cured sealant
material which seals around the respective stringer passing through
the respective rib mouse hole.
10. The aircraft assembly according to claim 8, wherein the rib
forms a fuel tank boundary, and the rib foot cleat and the sealant
material form a fluid-tight seal.
11. The aircraft assembly according to claim 10, wherein the rib
forms a boundary between a fuel tank and a dry bay, or between a
fuel tank and another fuel tank.
12. A method for sealing around a stringer passing through a rib
mouse hole in an aircraft assembly, comprising: providing a rib and
a stringer extending through a mouse hole of the rib; arranging a
rib foot cleat according to claim 1 over the stringer; attaching
the rib foot cleat to the rib; and injecting sealant through the
injection hole in the rib foot cleat to fill a gap between the
cleat channel and the stringer with sealant so as to seal the
gap.
13. The method according to claim 12, wherein the cleat channel
terminates at a first channel opening rim on one side of the cleat
body and at a second channel opening rim on an opposite side of the
cleat body, the method further comprising: forming a channel lip
that extends at least partially around an interior of the cleat
channel adjacent the first and/or second channel opening rim.
14. The method according to claim 13, further comprising drilling
off holes through the rib foot cleat and the rib after arranging
the rib foot cleat over the stringer and before attaching the rib
foot cleat to the rib.
15. The method according to claim 13, further comprising drilling
off holes through the rib foot cleat and the rib after arranging
the rib foot cleat over the stringer and before attaching the rib
foot cleat to the rib and wherein the lip(s) are formed after
drilling off the holes in the rib foot cleat and before the rib
foot cleat is attached to the rib.
16. The method according to claim 12, wherein the sealant is
injected in the injection hole by air pressure injection,
preferably by a sealant gun.
17. The method according to claim 12, wherein a flow of injected
sealant is stopped when sealant escapes from the cleat channel
18. A tool for forming a lip on a rib foot cleat having a cleat
body defining a cleat channel configured to be arranged over a
stringer, and an attachment flange for attaching the cleat body to
a rib, wherein the cleat channel is generally U-shaped and
terminates at a first channel opening rim on one side of the cleat
body and at a second channel opening rim on an opposite side of the
cleat body, the tool comprising: a tool body configured to be
placed against the cleat channel of the rib foot cleat, the tool
body having at least one recess which extends at least partially
around an interior of the cleat channel adjacent the first and/or
second channel opening rim; and a locating feature for aligning the
tool body against the cleat body of the rib foot cleat.
19. The tool of claim 18, wherein the tool body comprises two
respective recesses that extend around an interior of the cleat
channel adjacent the respective first and second channel opening
rim.
20. The tool of claim 18, wherein the tool is collapsible and the
tool body is flexible.
21. The tool of claim 20, further comprising at least one handle
for manually collapsing the collapsible tool.
22. The tool of claim 18, wherein the tool is made of nylon.
23. A method of forming a lip on a rib foot cleat having a cleat
body defining a cleat channel configured to be arranged over a
stringer, and an attachment flange for attaching the cleat body to
a rib, wherein the cleat channel is generally U-shaped and
terminates at a first channel opening rim on one side of the cleat
body and at a second channel opening rim on an opposite side of the
cleat body, the method comprising: providing the tool of claim 18;
inserting the tool in the rib foot cleat such that the tool body is
be placed against the cleat channel of the rib foot cleat;
injecting sealant in the at least one recess of the tool body;
curing the sealant and; removing the tool.
Description
RELATED APPLICATION
[0001] This application is incorporated by reference and claims
priority to United Kingdom patent application GB 2102308.0, filed
Feb. 18, 2021.
FIELD
[0002] The present invention relates to a rib foot cleat for
sealing around a stringer passing through a rib mouse hole in an
aircraft assembly, an aircraft assembly with the rib foot cleat, a
method for sealing a mouse hole, a tool for forming a lip on a rib
foot cleat, and a method for forming a lip on a rib foot cleat.
BACKGROUND
[0003] Aircraft wings extend spanwise from a root end nearest the
fuselage to a tip end. The wing has an upper wing cover having an
upper aerodynamic surface, a lower wing cover having a lower
aerodynamic surface, a leading edge and a trailing edge. Internally
the wing is typically configured to provide a fuel carrying volume.
A plurality of ribs extend generally chordwise between a front spar
and a rear spar, the front and rear spars extending generally
spanwise. The ribs are coupled to the spars and the covers to
create a `wing box` structure which is the main load bearing
structure of the wing. The ribs may also be used to segment the
fuel carrying volume of the wing into different bays. Stringers, or
longitudinal reinforcing members, extend generally spanwise along
the length of the wing on the interior side of the upper and lower
wing covers and pass through `mouse holes` in the ribs or rib feet.
Fuel may freely move through the mouse holes in the rib into the
neighbouring bay, or the mouse hole may be sealed to prevent the
flow of fuel. In order to accommodate potential geometrical
variations of the aircraft component shapes or dimensions the mouse
holes are necessarily fairly large.
[0004] A `dry bay` may be located within the wing directly above
the engine/pylon for an aircraft with under-wing mounted engines.
The dry bay does not contain any fuel and is a safety mechanism in
case of engine failure, e.g. a rotor disk burst. However, the dry
bay shares at least one rib with an adjacent fuel bay. Therefore, a
number of mouse holes need to be sealed to prevent fuel leaking
into the dry bay and keep the dry bay `dry`.
[0005] Sealing the dry bay presents a number of challenges, as it
has a large number of complex joints to the rest of the wing. Due
to the difficulty of gaining access to the area within the
assembled wing, reliable sealing of the dry bay mouse holes is
particularly difficult. Furthermore, the gaps between the mouse
holes and the stringers is very large, the shape of the stringer is
not simple and dry bay rib mouse holes are obliquely angled with
the dry bay rib, which provide further sealing challenges.
Accordingly, providing a repeatable and effective solution to
reliably seal each the dry bay rib mouse hole can be difficult to
achieve. Existing solutions for sealing rib mouse holes include
attaching a metal cleat over the stringer and fastening to the
adjacent wing cover and rib at the mouse hole location, and filling
the cleat with pieces of flexible open-cell polyurethane foam
filled with curable sealant. The foam parts are custom trimmed for
each location, and so are costly to procure and time consuming to
assemble to achieve the required high level of fluid tightness.
SUMMARY
[0006] According to an aspect of the invention, there is provided a
rib foot cleat for sealing around a stringer passing through a rib
mouse hole in an aircraft assembly, the rib foot cleat comprising:
a cleat body for attaching to a rib at a rib mouse hole and
defining a cleat channel configured to be arranged over a stringer;
and an injection hole through the cleat body in fluid communication
with the cleat channel to allow a sealant material to be injected
through the injection hole in to the cleat channel for sealing
around the stringer.
[0007] A cleat is a component fastened to support and hold
something in position. A rib is a chordwise extending structural
component of an aircraft wing. A rib mouse hole is a hole in an
edge of a rib. A stringer is a longitudinal reinforcing member.
Here, the rib foot cleat is positioned over a stringer and is
attached to the rib where the stringer passes through the rib mouse
hole, and is used to support and hold the sealant in place to seal
around the stringer.
[0008] The cleat channel may be generally U-shaped and may
terminate at a first channel opening rim on one side of the cleat
body and at a second channel opening rim on an opposite side of the
cleat body. A channel lip may extend at least partially around an
interior of the cleat channel adjacent the first and/or second
channel opening rim.
[0009] The channel lip may be configured to delimit the sealant
material that is injected through the injection hole.
[0010] The channel lip may optimise the amount of sealant required
to fully seal the joint. The channel lip may guide any excess
sealant that may otherwise protrude from the first and/or second
channel opening rim and be guided towards the stringer.
[0011] The channel lip may be made of sealant. The channel lip may
be made of a curable material.
[0012] The channel lip may be of the same material as the injected
sealant to create a seal. The injected sealant may be curable to
the channel lip.
[0013] The channel lip may be made of silicone, polyurethane,
polysulphide or silane-modified polymer.
[0014] The channel lip may be made of closed cell foam.
[0015] The rib foot cleat may comprise a first attachment flange
for attaching the cleat body to the rib, and/or a second attachment
flange for attaching the cleat body to a foot of the stringer.
[0016] A further aspect of the invention provides an aircraft
assembly, comprising a stringer reinforced cover and a rib having a
mouse hole with the stringer passing through the mouse hole in the
rib, and a rib foot cleat according to the first aspect arranged
over the stringer at the rib mouse hole and with cured sealant
material inside the rib foot cleat which seals around the stringer
passing through the rib mouse hole.
[0017] The rib may have a plurality of mouse holes each having a
respective stringer passing through, and a respective rib foot
cleat with cured sealant material which seals around the respective
stringer passing through the respective rib mouse hole.
[0018] The rib may form a fuel tank boundary and the rib foot cleat
and sealant may form a fluid-tight seal.
[0019] The injected sealant may fully seal one side of the rib from
the other.
[0020] The rib may form a boundary between a fuel tank and a dry
bay, or between a fuel tank and another fuel tank.
[0021] In a further aspect of the invention there is provided a
method a method of sealing around a stringer passing through a rib
mouse hole in an aircraft assembly, by providing a rib and a
stringer extending through a mouse hole of the rib, arranging a rib
foot cleat over the stringer, attaching the rib foot cleat to the
rib; injecting sealant through the injection hole in the rib foot
cleat to fill a gap between the cleat channel and the stringer with
sealant so as to seal the gap.
[0022] The cleat channel may terminate at a first channel opening
rim on one side of the cleat body and at a second channel opening
rim at an opposite side of the cleat body, and the channel lip may
be formed so as to extend at least partially around an interior of
the cleat channel adjacent to the first and/or second channel
opening rim.
[0023] Holes may be drilled through the rib foot cleat and the rib
after arranging the rib foot cleat over the stringer and before
attaching the rib foot cleat to the rib.
[0024] The lip(s) may be formed after drilling off the holes in the
rib foot cleat and before the rib foot cleat is attached to the
rib.
[0025] Drilling the holes in the rib foot cleat enables the rib
foot cleat to be correctly positioned over the stringer before the
sealant is injected. This provides a more effective seal as the rib
foot cleat may be positioned centrally over the stringer,
accommodating tolerances in the assembly.
[0026] The sealant may be injected in the injection hole by means
of pneumatic assistance, preferably by a sealant gun.
[0027] This provides a fast and repeatable method of introducing
the sealant into the rib foot cleat, reducing the time of
manufacture and assembly.
[0028] The flow of injected sealant may be stopped when sealant
escapes from the cleat channel.
[0029] Visually observing the sealant starting to escape provides
an easy method of verifying when the sealant has completely filled
the rib foot cleat, and therefore formed a reliable seal.
[0030] In a further aspect of the invention, there is provided a
tool for forming a lip on a rib foot cleat having a cleat body
defining a cleat channel configured to be arranged over a stringer,
and an attachment flange for attaching the cleat body to a rib,
wherein the cleat channel is generally U-shaped and terminates at a
first channel opening rim on one side of the cleat body and at a
second channel opening rim on an opposite side of the cleat body,
the tool comprising: a tool body configured to be placed against
the cleat channel of the rib foot cleat, the tool body having at
least one recess which extends at least partially around an
interior of the cleat channel adjacent the first and/or second
channel opening rim; and a locating feature for aligning the tool
body against the cleat body of the rib foot cleat.
[0031] The tool body may comprise two respective recesses that
extend around an interior of the cleat channel adjacent the
respective first and second channel opening rim.
[0032] The tool may be collapsible. The tool body may be flexible
to enable the collapsing of the tool. Alternatively the tool body
may be more rigid and incorporate a hinge between tool body
portions.
[0033] This enables the tool body to be removed easily from the rib
foot cleat without damaging the formed channel lips.
[0034] The tool body may have at least one handle for manually
collapsing the collapsible tool.
[0035] The tool may be made of nylon so that sealant does not
adhere to the tool.
[0036] This allows the tool to be flexible while not promoting
adhesion of the sealant to the tool itself. This encourages the
channel lips to adhere to the rib foot cleat as opposed to the
tool.
[0037] In a further aspect of the invention, there is provided a
method of forming a lip on a rib foot cleat having a cleat body
defining a cleat channel configured to be arranged over a stringer,
and an attachment flange for attaching the cleat body to a rib,
wherein the cleat channel is generally U-shaped and terminates at a
first channel opening rim on one side of the cleat body and at a
second channel opening rim on an opposite side of the cleat body,
the method comprising providing the tool, inserting the tool in the
rib foot cleat such that the tool body is be placed against the
cleat channel of the rib foot cleat; injecting sealant in the at
least one recess of the tool body; curing the sealant and removing
the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Embodiments of the invention will now be described with
reference to the accompanying drawings, in which:
[0039] FIG. 1 shows a plan view of an aircraft;
[0040] FIG. 2 shows the internal detail of part of an aircraft wing
assembly with a stringer reinforced cover and a rib;
[0041] FIG. 3 shows a rib foot cleat arranged over a stringer and
attached to a rib;
[0042] FIG. 4 shows a rib foot cleat;
[0043] FIG. 5 shows a tool for forming a channel lip on a rib foot
cleat;
[0044] FIG. 6 shows the rib foot cleat on the tool;
[0045] FIG. 7 shows a rib foot cleat with channel lips formed;
[0046] FIG. 8 shows the process of forming channel lips and
arranging a rib foot cleat over a stringer and injecting sealant to
seal a mouse hole between a rib and stringer;
[0047] FIG. 9 shows the assembly of FIG. 3 and the flow of injected
sealant;
[0048] FIG. 10 is a cross section of the rib foot cleat body and a
flow of injected sealant;
DETAILED DESCRIPTION OF EMBODIMENT(S)
[0049] FIG. 1 shows an aircraft 1 with starboard wing 2, port wing
3, fuselage 4, a nose end 5 and a tail end 6. The aircraft 1 is a
typical jet passenger transonic transport aircraft but the
invention is applicable to a wide variety of fixed wing aircraft
types, including commercial, military, passenger, cargo, jet,
propeller, general aviation etc. Each wing 2,3 has an upper and
lower wing covers 18, which are strengthened and stiffened by a
plurality of stringers 14 which extend generally spanwise along the
wing from the wing root near the fuselage to the wing tip.
Internally the wing is configured to provide a fuel carrying
volume.
[0050] A plurality of ribs 12 extend generally chordwise between a
front spar and a rear spar (not shown), the front and rear spars
extending generally spanwise. The ribs are coupled to the spars and
the covers to create a `wing box` structure which is the main load
bearing structure of the wing. The ribs also segment the fuel
carrying volume of the wing into different bays.
[0051] A `dry bay` 8 is located adjacent and above an under-wing
mounted main engine on the wing 2. The dry bay does not contain
fuel so that in the event of engine malfunction or failure, where
components of the engine may directly impact the wing, no leak of
fuel occurs. The dry bay is adjacent to at least one fuel tank bay
in the wing. The port wing 3 is constructed similarly.
[0052] FIG. 2 shows a portion of an aircraft wing assembly 20 of
the wing 2, in particular the rib 12, stringers 14, lower wing
cover 18 and rib mouse holes 16 through which the respective
stringers 14 pass. The rib 12 forms a boundary between a fuel tank
bay 11 and the dry bay 8. Rib 12 extends generally perpendicular,
vertically away from lower cover 18 and is connected to the lower
cover at a lower end by rib feet and is connected to the upper
cover at an upper end by rib feet (not shown). Rib 12 has a
plurality of mouse holes 16 at the lower edge and a plurality of
mouse holes at the upper edge (not shown). The rib mouse holes are
formed in the rib to enable each of the stringers to pass though
the rib without causing the requirement to fabricate any joints in
the stringers.
[0053] Stringers 14 extend continuously through the respective rib
mouse holes 16 of the rib 12. The stringer profile in FIG. 2 is
shown to be a `Z` stringer, however, it will be understood that any
number of stringer profiles may be used, such as omega, top-hat,
C-shaped; or any other suitable design. The mouse holes are sized
to closely match the profile of the stringer to minimise the gap
between the stringer and the rib, whilst allowing a clearance.
[0054] Between at least some fuel bays, fuel may be allowed to move
freely through the mouse holes in the rib. However between other
fuel bays this may be undesirable, and between a fuel bay and the
dry bay 8 the rib 12 must be sealed. This is achieved by sealing
around the stringer 14 that passes through each mouse hole 16.
[0055] FIG. 3 shows the detail of an aircraft assembly 22 in which
a rib foot cleat 21 is arranged over stringer 14a. In FIG. 3 the
stringer 14a has a top hat profile different than the Z-shaped
stringer 14 but any suitable stringer profile may be used. The rib
foot cleat may be made of any suitable material, such as metal or a
composite material. The rib foot cleat may be additively
manufactured. FIG. 4 shows the rib foot cleat 21 alone for
clarity.
[0056] The rib foot cleat 21 has a body 24 defining a cleat channel
34 configured to be arranged over the stringer 14a. The cleat body
may have a bell-shaped, arched or roof portion extending over the
cleat channel 34. The rib foot cleat 21 is arranged on one side of
the rib 12, and is preferably on the inside of the dry bay 8.
However, two rib foot cleats 21 may be placed one on either side of
one mouse hole 16.
[0057] The rib foot cleat body 24 has a first attachment flange 30
for attaching the cleat body to the rib 12. A second attachment
flange 32 extends perpendicular to the first attachment flange 30.
The second attachment flange is configured for attaching the cleat
body to a foot of the stringer 14a and the wing cover 18. The rib
foot cleat body may be a unitary structure comprising the first and
second attachment flanges 30, 32 and the arched portion defining
the cleat channel 34. The second attachment flange 32 may be formed
in two portions, one on either side of the cleat channel 34. Each
attachment flange 30, 32 has a number of fastener holes 28, used to
secure the rib foot cleat 21 to the rib 12 and stringer 14a/cover
18 respectively.
[0058] The rib foot cleat channel 34 may be generally U-shaped and
terminates at a first channel opening rim 34a at one side of the
cleat body 24 and a second channel opening rim 34b (shown in FIG.
6) at the opposite side of the cleat body 24. There is an injection
hole 26 through the cleat body that is in fluid communication with
the cleat channel 34 to allow sealant to be injected through the
injection hole 26 in to the cleat channel 34 for sealing around the
stringer 14a. The injection hole 26 may be formed in apex of the
arched portion of the rib foot cleat body 24. The injection hole
may be formed by drilling or through any suitable method. It will
be understood that the injection hole 26, or a plurality of
injection holes, may be positioned in any suitable area of the
cleat body 24 so as to be placed in fluid communication with the
cleat channel 34. Preferably a single, apex located injection hole
26 is provided.
[0059] The rib foot cleat channel 34 is shown in FIG. 4 as being
generally U-shaped and arranged over stringer 14a, which has a
top-hat stringer profile. However, it will be understood that any
suitable shape of stringer profile, such as C-shaped, Z-shaped; or
any other suitable design may be used. The rib foot cleat channel
34 and rib foot body 30 may be sized and modified to closely match
the profile of the stringer to minimise the gap between the
stringer and rib foot cleat channel 34, whilst permitting the rib
foot cleat channel 34 to be placed over the stringer and for
attachment of the rib foot cleat body 30 to the rib and to the foot
of the stringer.
[0060] To prevent sealant escaping from the cleat body 24 through
the channel opening rims 34a, 34b, the rib foot cleat 21 may
further include a channel lip 56 (shown in FIG. 7) that extends at
least partially around the interior of the cleat channel 34 or
adjacent to the first and/or second channel opening rim, 34a and
34b. The channel lip 56 is positioned in a way to act as a barrier
between the channel body 34 and the external environment and
preferably, to delimit the inserted sealant from exuding during the
injection process. The channel lip 56 is preferably formed along
the periphery of the channel rims 34a and 34b. However, it will be
understood that a number of channel lip designs may be employed to
seal a gap between the cleat body 24 and the stringer. For example,
a single lip may be formed along the centre of the cleat body 24,
such that when sealant is injected, only one half of the cleat
channel 34 is filled. Alternatively, the channel lips may be formed
partially down the peripheral edges 34a and 34b, or from a set
distance from the peripheral edge into the cleat channel
[0061] Preferably, two channel lips 56 are formed adjacent to the
respective first and second channel opening rim 34a and 34b. The
channel lips are preferably formed before the rib foot cleat 21 is
attached to rib 12 and stringer 14a. The channel lips may be formed
from sealant. The lips may be made of any curable sealant, such as
silicone, polyurethane, polysulphide, or silane-modified polymer.
Preferably, the same material used for forming channel lips 56 is
used to inject into the injection hole 26 and into the rib foot
cleat channel 34. The channel lips 56 are formed to guide the
injected flow of sealant 60 in to the gap 66 so that it protrudes
from the bottom of the rib foot cleat 21, as shown in FIG. 9,
indicating that the injected sealant has completely filled the area
between the stringer 14a and rib foot cleat body 24.
[0062] The channel lips 56 shown in FIG. 7 are shown as being
generally cuboid shaped with a rectangular cross-section. However,
it will be understood that any suitable channel lip 56 shape may be
formed within the rib foot cleat channel 34. For example, the
channel lips 56 may be formed with a triangular cross-section, with
a base contacting and formed at least partially around the interior
of the cleat channel 34 and an apex of the triangle extending into
rib foot cleat channel 34.
[0063] Alternatively, the channel lips 56 may be formed with a
semi-circular cross section, with a base contacting and formed at
least partially around the interior of the cleat channel 34 and a
rounded peak extending into the rib foot cleat channel 34.
[0064] When the channel lips 56 are formed with an apex or a
rounded peak, the channel lips 56 are easier to detach from the
tool 40 after curing (discussed further below) and compress more
easily against the stringer. This enables the channel lips 56 to be
manufactured easier and quicker. The channel lips 56 also conform
to the profile of the stringer 14a better once the rib foot cleat
body 30 is arranged over the stringer, improving the seal between
the rib foot cleat and the stringer.
[0065] Alternatively, the channel lips 56 may be formed separately
from the tool 40 and the rib foot cleat. The pre-formed channel
lips 56 may then be adhered on to the rib foot cleat channel 34
using any suitable form of adhesion. The adhesive may be of the
same material used to form the channel lips 56.
[0066] Alternatively, the channel lips 56 may be formed by closed
cell foam that is positioned within the rib cleat channel 34. The
closed cell foam may be positioned within the channel, or it may be
adhered on to the walls of the channel 34. The manufacturing and
assembly time of the sealed mouse hole may be reduced if closed
foam is used for the channel lips, as less time may be required to
adhere the closed cell foam than to form the channel lips of
curable sealant.
[0067] FIG. 5 shows an exemplary tool 40 that is used to for
forming the channel lips 56 from curable sealant material on the
rib foot cleat 21. As shown, the tool 40 has a profile that
substantially corresponds to the profile of the rib foot cleat body
24. As such, it will be understood that a number of profiles of
tool 40 may be used, depending on the profile of the rib foot cleat
body 24. Tool 40 in FIG. 5 is shown as being substantially U-shaped
in profile. The tool has two recesses 44a and 44b that correspond
to the preferred positioning of the channel lips 56 along the first
and second channel rim opening, 34a and 34b. These recesses extend
at least partially along the interior of the cleat channel 34,
adjacent to the first and second channel opening rim, 34a and 34b.
The tool 40 may alternatively only have one recess, or multiple
recesses configured to correspond to the channel lips 56 that are
to be formed on the rib foot cleat channel 34.
[0068] The tool 40 shown in FIG. 5 has locating features 46 that
are configured to support the rib foot cleat when positioned on the
tool, as shown in FIG. 6. Locating features 46 may be a protrusion
used to support the first attachment flange 30 and/or the second
attachment flange(s) 32. Locating features 46 support the rib foot
cleat 21 while channel lips 56 are being formed and (at least
partially) cured, as described below. The features 46 may be
temporarily clamped to the flange 30 by means of suitable spring
c-clamps or similar to reduce the possibility of the tool from
moving during the formation and the curing of the lips 56.
[0069] Once the tool 40 is inserted into the rib foot cleat 21 (or
vice versa), sealant is inserted, e.g. pasted or injected, into the
recesses, 44a and 44b. Preferably, a nozzle with a narrow,
preferably tapered tip is used to insert the sealant. The narrow
tip ensures that once inserted, the nozzle can be used to insert
the sealant into the bottom of recesses 44a and 44b (as shown in
FIGS. 5 and 6). This ensures that the sealant is fully inserted in
the recesses 44a and 44b and reduces the likelihood of air bubbles
forming in the resulting channel lips 56.
[0070] The shape of the recesses 44a and 44b can be modified
depending on the desired final shape of the channel lips 56 to be
formed. The resulting channel lips 56 are allowed to cure while the
tool 40 remains supporting the rib foot cleat. This ensures the
channel lips adhere to the rib foot cleat channel 34. The channel
lips 56 may be cured faster by heating channel lips 56 during the
curing process. This is done by heating the tool 40 and the rib
foot cleat after the sealant has been inserted into the recesses
44a and 44b. Any suitable form of heat treatment may be used. This
reduces the time required to manufacture the channel lips 56. Once
the channel lips have cured, the tool 40 is removed.
[0071] As shown in FIG. 5, tool 40 may have a flexible `hinge` line
45 along the middle of the tool. Once the channel lips 56 have
cured, the tool may be collapsed by rotating or flexing about line
45 to permit easy dismantling of the tool without disturbing the
channel lips 56. Tool 40 may further comprise handles 48 to help
facilitate manually collapsing the tool within the rib foot cleat
21. However, it well be understood that hinge line 45 may be at
along any position of the tool to permit collapse. Any flexible,
semi-rigid, or hinge jointed rigid construction of the tool body 42
that enables the tool the collapse about the rib foot cleat 21 to
enables removal of the rib foot cleat after forming the channel
lips 56 would be suitable.
[0072] The tool may be made of any material, such as metal or
plastic, but preferably, the tool is manufactured by additive
manufacturing. The tool may be made of ABS, PLA, PC but preferably,
is made of nylon. Manufacturing the tool body 42 from nylon allows
the sealant to be supported in position to cure, but does not
encourage the sealant to adhere to the tool, thereby facilitating
easy removal of the tool without requiring any undesirable release
agent. The surface of the tool 40 may also be polished to further
discourage the sealant from adhering to the tool. This may be done
by any suitable method, such as heat treating or burnishing the
tool to re-melt the surface of the tool after printing or rubbing
the surface of the tool 40.
[0073] A release agent may also be used on the tool 40 to further
discourage the sealant adhering to the tool. The tool 40 may be
coated with the release agent prior to forming the channel lips 56.
Preferably, once the channel lips 56 are formed, the tool 40 is
cleaned to remove any residual release agent, before a new layer of
release agent is coated on the tool. The release agent may be any
suitable release agent, such as sodium alginate. FIG. 7 shows the
rib foot cleat arrangement 56, with rib foot cleat 21 removed with
the tool, with channel lips 56 formed on the first opening rim 34a
and second opening rim 34b of the cleat body 34.
[0074] FIG. 8 shows the steps of assembling the rib foot cleat 21,
with optional steps for forming the channel lips 56. The rib foot
cleat is placed against the rib 12 and arranged over the stringer
14a to identify the final position of the rib foot cleat. The rib
foot cleat should be centred on the stringer. Fastener holes 28 are
drilled off through the rib foot cleat 21 (and the rib and the
stringer foot) before removing the cleat from the rib 12 and
stringer 14a. The injection (or inlet) hole 26 may be formed in the
cleat body 24 at any time prior to offering up and drilling off the
fastener holes 28. Alternatively the inlet hole may be formed
before forming the lips, or alternatively, the inlet hole may be
made after the sealant lips have been made.
[0075] Once the rib foot cleat 21 has been removed from the rib 21,
the fastener holes 28 may be cleaned and deburred before the rib
foot cleat is then offered up again to the rib for final fasteners
installation.
[0076] Where the optional channel lips are to be formed on the rib
foot cleat, after drilling off the fastener holes, the tool 40 is
inserted in the rib foot cleat (or vice versa) and sealant is
injected into recesses 44a and 44b and left to cure. Once the
channel lips 56 have been cured, the tool 40 is removed.
[0077] The rib foot cleat 21 is then arranged on the stringer 14a
and against rib 12, before final fasteners are installed in the rib
foot cleat 21 using the fastener holes 28 to fasten the rib foot
cleat 21 to the rib 12 and the foot of the stringer 14a.
[0078] Once fastened, sealant 60 is injected through sealant
injection hole 26, as shown in FIGS. 9 and 10. Sealant 60 is
injected through the injection hole 26 to fill gap 66 (shown in
FIG. 10) between the cleat body 24 and stringer 14a. The sealant is
injected until sealant visibly protrudes from the rib foot cleat
channel 34. This allows an easy method of fully sealing rib foot
cleat 21 after it has been secured to the rib 12 and over the
stringer 14a. This also ensure reliability of the seal as visual
inspection reduces the probability of forming an incomplete seal.
The injectable sealant provides faster installation of the rib foot
cleat 21.
[0079] The sealant injected into the channel of the rib foot cleat
fills the gap 66 between the stringer profile and the interior of
the cleat channel 34 to fully seal the cavity and prevent fuel from
moving through the mouse hole 16.
[0080] As mentioned above, the injectable sealant 60 is preferably
made of the same type of material as the sealant used to form the
channel lips 56. This is advantageous as once the injected sealant
is cured, it will fuse with the channel lips 56 and form one
cohesive seal in gap 66. This is advantageous as this promotes an
effective seal.
[0081] The injectable sealant 60 may be introduced by any suitable
means, but preferably the injectable sealant 60 is supplied from a
pre-filled sealant cartridge 64 with a nozzle attached which is
placed within a gun (not shown). The gun may use mechanics, air
pressure or electromechanical drives to facilitate quick injection
of the injectable sealant 60. FIG. 10 shows a cross section 62 of
the cleat body 24 with sealant in the cartridge 64 injecting
sealant using flow of sealant 60. As shown, the flow of sealant 60
will go through inlet hole 26 and around stringer 14a, filling gap
66. The nozzle may be extended in length or bent appropriately in
order to assist access into areas which are difficult to access
within the wing assembly.
[0082] While the invention relates to providing a fuel tight
boundary between a dry bay and fuel bay within an aircraft, it will
be understood that similar designs may be implemented in any
boundary within a wing, aircraft, or any other industry.
[0083] Where the word or appears this is to be construed to mean
`and/or` such that items referred to are not necessarily mutually
exclusive and may be used in any appropriate combination.
[0084] Although the invention has been described above with
reference to one or more preferred embodiments, it will be
appreciated that various changes or modifications may be made
without departing from the scope of the invention as defined in the
appended claims.
[0085] While at least one exemplary embodiment of the present
invention(s) is disclosed herein, it should be understood that
modifications, substitutions and alternatives may be apparent to
one of ordinary skill in the art and can be made without departing
from the scope of this disclosure. This disclosure is intended to
cover any adaptations or variations of the exemplary embodiment(s).
In addition, in this disclosure, the terms "comprise" or
"comprising" do not exclude other elements or steps, the terms "a"
or "one" do not exclude a plural number, and the term "or" means
either or both. Furthermore, characteristics or steps which have
been described may also be used in combination with other
characteristics or steps and in any order unless the disclosure or
context suggests otherwise. This disclosure hereby incorporates by
reference the complete disclosure of any patent or application from
which it claims benefit or priority.
* * * * *